(a) Field of the Invention
The present invention relates to a dry etching method and an apparatus for performing dry etching, and more particularly to the dry etching method and apparatus including multiple cooling paths.
(b) Discussion of the Related Art
Equipment for manufacturing semiconductor devices is generally classified as either equipment for preceding processes or equipment for subsequent processes. The equipment for preceding processes is used to form a photoresist pattern on a semiconductor substrate, such as coating a photoresist layer, exposing, and developing. In contrast, the equipment for subsequent processes is used for various processes related to a patterned substrate, such as an ion implantation process wherein impurity ions are implanted into the patterned substrate, an etching process wherein a target layer is selectively removed by using the photoresist pattern, a deposit process wherein a thin film is deposited on the semiconductor substrate, and a metallization process wherein a circuit pattern is interconnected.
Etching is generally performed by either a wet etching apparatus or a dry etching apparatus. The known dry etching apparatus includes a lower electrode disposed opposite an upper electrode in an etching chamber. In the known dry etching apparatus, a wafer is loaded on the lower electrode, and process gases are supplied and converted into plasma by the upper electrode.
FIG. 1 shows an example of a lower electrode in the known dry etching apparatus. As shown in the figure, the lower electrode 102 defines cooling paths 104 in which cooling gas flows. A clamping part 106 presses a wafer W loaded on the lower electrode 102, such that the wafer W is held on the lower electrode 102, and is cooled by the cooling gas flowing in the cooing paths 104 during etching of the wafer W.
When the known dry etching apparatus is used to etch the wafer W, the uniformity in the thickness of the remaining layer after the etching process depends on process conditions, such as a source power of the dry etching apparatus, chamber pressure, ratio of process gases, and uniformity of an etch target layer. The uniformity in thickness of the remaining layer is also largely dependent on a rear surface temperature of the wafer.
FIG. 2 is a graph showing etch rate and uniformity in thickness of the remaining layer on the wafer as a function of the rear surface temperature of the wafer. As shown in FIG. 2, both the etch rate and the uniformity in the thickness of the remaining layer are increased as the rear surface temperature of the wafer is increased.
FIG. 3 is a graph showing simulated data of the thickness of the remaining layer as a function of position after etching with the known dry etching apparatus. As shown in FIG. 3, the remaining layer is not uniformly thick.
As described above, in the known dry etching apparatus the temperature of the lower electrode is uniform over the entire rear surface of the wafer. However, uniformity, or lack thereof, of the deposited etch target layer is not accounted for during the setting of process conditions. The uniformity of the deposited etch target layer affects the uniformity in the thickness of the remaining layer. Therefore, it is difficult to improve the uniformity in the thickness of the remaining layer.